Over the Counter Zinc Additive
i wonder sometimes if it is necessary...lots of propaganda and i have read info that says it isn't necessary.The zinc products have become a billion dollar industry....even the cam manufacturers are in on the action.But like most, i use it "just in case" and have always added GM EOS.
I asked the same question. My current conclusions FWIW:
1) Yeah, it is a real problem. Things really did go to crap right when the ZDDP's level dropped by almost 50% around 2005-2006. The faster ramps in some cams today make it even more of an issue.
2) The need for ZDDP varies with the lifter to lobe pressure (based on readings research papers).
3) A stock spring setup and stock cam is probably going to be fine with the newer, lower ZDDP levels. (But, no guarantees just because I think so!)
4) Your standard 1st level step up in performance springs pressures, to something over 100 lbs closed and 250-300 lbs open spring pressures means you had better get the ZDDP PPM's back up the 1200-1400 PPM range.
5) If you are at, say, 400+ lbs of open spring pressure, I personally don't know the needed levels. A recent research paper shows that the amounts needed are related to the pressure of the surface contact, so it stands to reason that more may be needed than 1200-1400 PPM.